Triblock copolymers having poly(4-vinylpyridine) end blocks and a polybutadiene center block can be prepared by sequential anionic polymerization of butadiene and of 4-vinylpyridine using an organolithium initiator; see M. S. Jacovic, "Ionomer-like materials based on 4-vinylpyridine copolymers," Maromol. Chem., Rapid Commun, vol. 10, 217-225 (1989).
Quaternization of triblock polymers of polystyrene-polybutadiene-polyvinylpyridine is disclosed by Ohnuma et al. in Chemical Abstracts, 111(16):134883 (1989).
Quaternization of poly(4-vinylpyridine) is known: Boucher et al., "Kinetics and Mechanism of the Quaternization of Poly(4-vinylpyridine) with Ethyl, n-Propyl, n-Butyl, n-Hexyl and Benzyl Bromide in Sulfolane", J. Chem. Soc. Faraday Trans. I, 73., pp. 1629-1635 (1977).
Diblock and triblock copolymers of butadiene and 2-isopropenylpyridine have been synthesized by anionic polymerization, using a difunctional lithium initiator: Soum et al., "Synthesis and Characterization of New Block Copolymers of Butadiene and 2-isopropenylpyridine," Polymer, vol. 29, pp. 1528-1534 (August, 1988).
U.S. Pat. No. 3,639,523 issued to Hayhr et al. Feb. 1, 1972 relates to adhesives having improved green strength, building tack, solvent resistance and high temperature stability. The architecture of the disclosed polymer is A-C-B-C-A where A is vinylpyridine, B is a conjugated diene, and C is a monovinyl arene. This reference does not disclose or suggest that this material can be used as a flexographic printing plate.
Triblock copolymers of polystyrene-polybutadiene (or polyisoprene)-polystyrene have been used in the preparation of photosensitive printing plates: U.S. Pat. No. 4,323,637, Chen et al., "Use of Cover Sheet and Interposed Flexible Film with Block Copolymer Compositions" (1982). The copolymers were not quaternized, nor were the resulting formulations water-developable.
U.S. Pat. No. 4,045,231 et al. discloses triblock polymers of the type polystyrene-polybutadiene-polystyrene for use in printing plates, but the polymers were not quaternized. Such plates are not water-developable.
U.S. Pat. No. 4,162,919, Richter et al. (1979), discloses a 2-block copolymer of styrene-isoprene (or butadiene) for use in flexographic printing plates.
U.S. Pat. No. 4,245,027, Takeda et al. (1981), discloses a photosensitive composition comprising copolymers of vinylpyridine and a polyvinylidene halide, optionally with an olefin, e.g., butadiene or isoprene, plus a light sensitizing element, e.g., iodoform, quinones, or diazonium salts, capable of forming a quaternary salt with the polyvinylpyridine on heating or on exposure to actinic light. The instant invention differs, inter alia, in that our triblock copolymer has no polyvinylidene component, and further in that when we quaternize it is prior to formulation and exposure.
U.S. Pat. Nos. 4,271,259 and 4,272,610, both to Breslow et al. (1981), disclose a copolymer of butadiene or isoprene with vinyl pyridine as a component in a photosensitive composition. The copolymer is not specified as ABA, and it is not quaternized. The composition requires an oxidizable component containing allylic hydrogen and a photooxygenation sensitizer.
U.S. Pat. No. 4,430,417, Heinz et al. (1984), discloses ABA triblock copolymers in making flexographic printing plates. A is styrene-butadiene, B is isoprene.
U.S. Pat. No. 4,179,531, Heinz (1979), discloses ABA triblock copolymers ("Kraton".sup.(R) --Shell Chemical Co.) in making printing plates where A is a styrene and B is a diene such as isoprene or butadiene. A polythiol is required in the formulation.
U.S. Pat. No. 4,045,231, Toda et al. (1977), discloses a styrene-butadiene-styrene triblock copolymer in a printing plate formulation.
Chem. Abstracts 111(6):39978k, Moeller et al., discloses iodine doped AB diblock copolymers of poly(2-vinylpyridine) and either polybutadiene or polystyrene.
Chem. Abstracts 109(10):74182b, Shimazaki et al., discloses triblock copolymer, polystyrene-polyisoprene-poly(vinylpyridine) quaternized with chloromethylstyrene. Use in photosensitive compositions is not disclosed.
Chem. Abstracts 104(20):169705k, Y. Mihaki, discloses isoprene-styrene-4-vinylbenzyldimethylamine block copolymers treated with di-iodopropane to prepare an amphoteric ion exchanger.
Chem. Abstracts 103(20):166031f, Lelah et al., discloses quaternization of triblock poly(styrene-butadiene-4-vinylpyridine), with crosslinking of the butadiene segment and sulfonation of the styrene block.
Chem. Abstracts 101(6):39114u, Kudose et al., discloses quaternizing triblock butadiene-styrene-4-vinylpyridine copolymer with methyl bromide.
Chem. Abstracts 88(2):75242, Fielding-Russell et al., discloses HCl quaternization of butadiene-styrene-2-vinylpyridine block copolymer.
European Patent application 91116973.8 published Apr. 15, 1992 discloses various symmetrical and asymmetrical block copolymers made of styrene, isoprene and methylactylic acid for use in elastic relief printing plates.